1. Field of the Invention
The present application relates generally to oil field devices and, more particularly, to a plunger assembly with an internal dampening system.
2. Description of Related Art
The oil and gas industry has been drilling holes and removing natural crude oil for decades. Wells contain any number of contaminants, particulates, and water along with the gas/oil being sought. If water is not removed, pressure of the hydrostatic head of water in the surface tubing will become greater than that of the bottom hole pressure, thereby essentially sealing the formation and shutting in the well. Gas cannot on its own pressure typically flow to the surface.
Plungers are downhole tools used by operators to remove contaminants and water from productive natural gas wells. A plunger acts as an artificial lift. In operation the plunger passes down through the well until it reaches a contact point, at which point, potential energy of the plunger falling in the well acts to partially restrict the flow of working fluid through the plunger. Pressure beneath the plunger builds and raises the plunger in the well, thereby pushing out the liquids and contaminants above the plunger.
Typical plunger lift systems rely on the potential energy of the system falling in the well to generate enough force on a dart to seat the dart and create a seal. In other words, the contact itself sets the dart and generates the seal. Such designs generate a lot of forces on the tool and the equipment (i.e. the stop) at the bottom of the well upon impact. Tools are commonly damaged from the impacts.
Another disadvantage of traditional plungers are the inability to operate with various wells having different production rates. Wells that are high flowing provide a higher up force on a plunger system than a well that is low flowing. In order for a plunger to fall in a high flowing well, more fluid has to pass through the plunger. Tools typically fall slower through the wells that are high flowing. Low flowing wells allow tools to fall at much greater speeds and require a tool to restrict the flow of fluid through the plunger in order to regulate the speed of descent. If the speed is incorrectly gauged, a tool may struggle to fall in the well or a tool may fall too fast and incur damage upon impact at the bottom.
An additional disadvantage is the effect of a “drift diameter” restraining the size of the plunger in relation to the well bore. The drift diameter is the minimum inside diameter of the tube in order to pass a ridged tool of some set length through it. Tools are designed to have a maximum diameter no greater than the drift diameter of the tubing. This results in the tools having a gap between them and the ID of the tubing. The large annulus or gap between the tool and the tubing that the tools passes through are one reason why tools tend to be inefficient because plunger lift tools work on a pressure gradient between fluid beneath the tool and fluid above the tool. Leaks between the tool and tubing impact the pressure gradient.
Another disadvantage of conventional plunger lift systems are the particulates (i.e. sand) in the working fluid. The working fluid passes within the gap between the plunger lift system and the casing at increased speeds resulting in tools abrading quickly. Additionally, the leak leads to turbulence created around the down hole edge of the tool when it expands after passing through the leak.
A new plunger lift assembly tool is required that is adaptable for use on wells of varied flow rates, minimize abrading, and corrects for the constraints associated with the drift diameter.
Although great strides have been made, considerable shortcomings remain.
While the assembly and method of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the application to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application as defined by the appended claims.